• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 29 subscribers
  • Views 221 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV10987: DRV10987 start-up failure at sometime.

Chris Jiang
Prodigy 120 points
Part Number: DRV10987

Hi .

As the title ,my application the BLDC can't start-up success at sometimes.

I got the print information of DRV10987. Regster 0X00 Value:0004( lock2 ,abnoamal Kt),Kt value=12.38, Speed=2580 RPM(the FG frequence is 172Hz,my closed threshold is 179.2Hz).

Abornally ,the BLDC doesn't enter closed loop state.My config Kt=10.12  and the setting range of KT is between 2kt and 1 / 2kt.The Kt=12.38 is in the normal range

I don't understand why the error of KT is reported at this time.

When lock2 is triggered,then the U/V/W will set Hi-Z and reset the register,about 5s(t lock-off) after restart the BLDC? but  my applycation is that when lock2 is triggered,

about 3s after the kt=6.88, Spd=9250(FG frequence is 595Hz),seems have entered the closed loop . 

Please help to see how to solve this problem ,ths.

Following is my EEPROM config:

90:0X102E

91:0X0B3A

92:0X08C0

93:0X12EB

94:0X3F0F

95:0XF843

96:0X006A

Motor parameters :

Best wishes and regards!

chris

  • 0
    TI__Expert 3535 points

    Hi Chris,

    Thanks for posting on the MD forum. 

    I'm reviewing your question and I will get you an answer by the end of the day.

    Regards,

    Michael

  • 0
    TI__Expert 3535 points

    Hi Chris,

    1. We have a video of how to measure the BEMF constant, please watch this and directly program the measured Kt. 

    Watch the video here : https://training.ti.com/how-spin-drv10x-family-devices-part-1

    2. Next, please disable closed loop. After disabling closed loop, spin the motor in open loop and keep tuning the lead time until the estimated Kt matches the programmed kt (10.12).


    3. After this, enable closed loop and try to spin the motor again.


    If the above steps don't work, try step 4.


    4. If you still see this issue, you can try disabling the abnormal Kt fault. When the abnormal Kt fault is disabled the device will still check if estimated Kt is between 2x programmed Kt and 1/2 programmed kt. If the estimated Kt is outside of this range, then the device will report an error but it will not trigger a fault (The motor will continue to spin/the outputs will not be in high - Z).


    What is the maximum speed of the motor?

    Thanks,

    Michael

  • 0 in reply to Michael Arrant
    Prodigy 120 points

    Hi Micheal:

    1.I  understand you said the steps,but the start-up failure frequnce is very low ,about 1/400. It's very difficult to imitate. 

    2.My applycation is used for laser colorwheel.When motor has mistake,the laser should turn off immediately, otherwise the colorwheel will be damaged.If we disabled the abnormal Kt fault,when the connection of U/V/W is not good,the MCU can't handle exception in real time .

    3.My MCU can read the register of DRV10987 at the real time.As described above,I can't understand the process of the start-up failure.For eg,the real time Kt is in the normal rang of 1/2Kt and 2Kt,but lock2(abnormal Kt) is found.And after lock2 is tiggerred,the U/V/W will turn to Hi-Z state,after 5s(t lock_off time) restart the DRV10987.But  about 3s after,MCU read the Kt and Speed is normal, have enterred the closd loop.It's means the DRV10987 may works normally after lock2 happened and the DRV10987 didn't disabled the U/V/W to Hi-Z. By the way ,the lock0~lock5 is only be tiggerred at the closed loop?

    4.The max Speed of the motor is 10080 R/min.

    5.I want to Increase the number of start-up attempts .The first start-up failure then clear the 0X00 and try the second....So , I can clear the register at any time when the power is on?

    Best wishes and regards!

    chris

  • 0 in reply to Chris Jiang
    TI__Expert 3535 points

    Hi Chris,

    I will review this with my team tomorrow and get back to you in the afternoon.

    Thanks,

    Michael

  • +1 in reply to Chris Jiang
    TI__Expert 3535 points

    Hi Chris,

    Once this device sees a fault, the motor will stop spinning for 5 seconds. After this 5 seconds passes, the motor will start to spin again. It's not possible for the motor to start spinning again before the 5 seconds has passed, unless you clear faults during this time period. The way the faults are cleared is by writing 0xFF to the register which clears the bits.

    Please follow the steps I provided in my above post as I think this will resolve your issue.

    Thanks and good luck,

    Michael

  • 0 in reply to Michael Arrant
    Prodigy 120 points

    Hi Micheal：

            OK，thanks.

    Best wishes and regards!

    Chris